Shock absorber



March 18 19 F. E. POIN DEXTER SHOCK ABSORBER Filed Nov. 16. 1920 the shell 6 and base 2. The plunger com shoulder to" limitone movement-of the er. 1%, ldfid.

IIEIQl'KLIN WRYPGINDEXTER, OF ST. LGUIS, MISSOURI, ASSEGNQR, BY NE A5- SIG S, Ti BMFJAIYHN S. DAVIDSDN, OF DENTQN, Tmfifi.

SHGCE assesses.

Application filed ZTcvember 18, 1920. Serial No. 424,450.

To @ZZ whom it may concern.-

Be it known that T, FRANKLIN E. Porn"- nr rrnn, a citizen of the United States of i-sa, residing at St. Louis, State of i, have invented certain new and Tim rovements in Shock Absorbers, h t e following is a specification.

shock absorbers wherein a main premure chamber is opened to the action of a pump operated in the relative movement of the parts of the shock absorber, to thereby vary the pressure in such main chamber in .accord-ance with load conditions.

The present application is designed par ticularly as an improvement upon a copending application filed by me February 2 1, 1920, Serial No. 360,666, and in certain characteristic details tends to a simplification of construction and operation.

In the drawings-:'

Fig. 1 is a vertical section of the improved shock absorber.

Fig. 2 is an elevation of the same showing a slightly'modified form of support.

In the preferred construction illustrated, the shock absorber comprises what may be termed a casing 1, made up of a cast base 2 having a cylindrical bore 3 extending therethru. The upper portion of the bore is enlarged at 4, resenting a lower limit shoulder 5. A cylindrical shell 6 is fitted in and extends above the base, the shell being connected to the base preferably by the threaded connection 7, the lower edge of the shell resting upon the shoulder 5. The upper endof the shell is designed to receive a cap 8, which may be, and preferably is, removable thru a threaded connection 9.

A plunger 10 is 'slidably mounted within prises a hollow cylindrical body, the upper portion' of which slidably fits the shell 6,

-while thelower portion slidably fits the base 2, the juncture between these respec-' tive 1portions of theplunger presenting a der 11, which may cooperate with the plunger relative to the shell. l

by "a ftransverse partition 12 near the lower endto thus provide a compartment 13 benis invention relates to an improvement voir, above said partition. A valve nipple 15 is threaded thru a central opening in the partition 12, and has an interior reduced passage 16 opening near the bottom of the chamber 13. An upwardly opening valve 17 controls this passage, the passage being somewhat enlarged above the valve as shown. A pump cylinder 18 is secured to that portion of the valve nipple extending above the partition 12, being preferably threaded on the nipple as at 19 and further secured by a transverse pin 20, which also forms a limit for the upward movement of the valve.

The upper end of the plunger 10 is formed as a reduced upwardly extending neck 21, and the pump cylinder 18 passes thru and beyond this neck, there being a space 22 between thepump cylinder and neck. The upper end of the plunger is closed by a plate 23 on which is arranged the lower end of-a coil spring 24. A s rlng retainer 25, engages the lower coils 0 such spring, and said retainer and'plate 23 is held in position b a nut 26 threaded upon the upper end of t e pump cylinder. When for any reason the air pressure Within the main pressure chamber 1s not snfficlent to support the load, the upper end of the spring 24: in contact with cap 8, and said spring assists 1n cushioning the relative movements of the plunger and casing, and

removably secured in a plug 28 closing anopening in the upper end of the cap 8. The rod 27 extends within .the pump cylinder 18 and is provided at its lower end with a valve nipple 29 having a reduced passage 30 formed at the upper endto providea.

valve .seat controlled by an upwardly opening" valve 31. The passage 30 above the valve communicates with the pump cylinder thru ports 32. A piston packing 33, of the usualpcup washer formation is secured towand carried by the valve nipple 29, to thereby rovide an operative pump piston within t ecylinder 18. The lower portion of -the pump cylinder 18 provides what may be termed a pump chamber 34:, and this a series of slots 3 Q Lessee? chamber, at its lower end, is in communication with the oil reservoir 14 thru a small opening 36. Above the wall 0 the pum cylin or is formed with anda tube 38 is secured to the exterior of the pump cylinder to cover the slotted area of such cylinder. Obviously in that stroke of the pump piston which carries such piston within the area of the slots 37, no pumping action will result, as the ressure equahzes around the piston thru t e slots.

The closure plate 23 for the upper end of the plunger is formed with an opening or openings 39 whereby oil accumulating above the plunger may gradually find its way into the oil reservoir 14, this opening 39 also serving to permit gradual equalization of pressure above the plunger and within the oil reservoir.

The oil accumulating in the main pressure chamber above the plunger will lubricate the plunger in operation, there being formed in the body of the plunger a passage 40 opening thru the side of the plunger at the upper end and thru the partition 12 atthe lower end whereby the excess oil finding its way between the plun er and casing will be delivered to the cham r 13.

Packing 41 is arranged between the upper end of theplunger and casing, said packing being secured to the upper end of the plunger outwardlyof the neck 21 and having its marginal edge held in desired con, tact with the spreading wedge ring 42 supported and positioned by springs 43 deppxiliding from the plate 23. A wiping pac g 44 is arranged between the intermediate ortion of the plunger and casing, such ac ing strip being secured to the plunger t u a spring ring 45 overlying the stripand forcing the same into a groove 46' in the plunger. The upper edge of the packing strip is held with desired pressure against the shell 6 of the casing by a spreading ring 47 seated in a channel 48 formed in the plunger. The oil that escapes by packing 41 is thus returned to chamber 13 from which it is pumped back into main pressure chamber.

That portion of the plunger extended below the bottom of the chamber 13 is partly cutaway, as at 49, and the corresponding portion of the base is similarly cutaway at 50, this permitting the introduction of the spring end to be connected. A spring connecting means for the plunger is shown at 51, while in the preferred form shown in Fig. 1, the base 2 is integrally formed with an outstanding car 53 whereby a bracerod to another air spring can be fastened At 56 is shown threaded holes for bolting air springs to chassis of automobile.

The hole 58 serves as an air inlet to slidump chamber, the

' conditions.

shell 6 of the casing by a 52 having an openingin joint between main piston and part 2 being suiiiciently loose to permit air to flow into space above shoulder 5.

The lower end of the chamber 13 is provided with a removable plug 56 for clean out purposes. p

In Fig. 2 is shown a hinged connection for securing the air spring to chassis, thus permitting the increase in length of car spring under compression and making the use of a shackle unnecessary. The connecting' bar 54 is arranged for hinged connection between the car 55 and the chassis 57 The operation of the improved shock absorber is substantially similar to that ,described in the co-pending application referred to. At each relative movement of the plunger and casing, there is a resultant pumping action of the pump, and this without regard to the extent of such movement. Therefore the pressure in the main chamber above the plunger will at all times be automatically governed in accordance with load It will (be understood that at each'upward and suction stroke of the pump piston, there is a tendency todraw into the pump chamber, oil from the reservoir 14,

but due to the restricted opening 36, the flow of the oil is insuiiicient to compensate for the suction and hence air from the atmosphere, together with some oil from the chamber 13 will be drawn into the pump chamber to compensate for the suction. On the return or pumping stroke of the piston, the tendency to displace the oil in the pum chamber is restricted by the opening 36, an hence such oil acts to a large extent as a base for the pump chamber, so that the air above this oil will be forced past the piston, thatis past the valve 31 and thru the o ning 32 and into the main pressure cham er. In that relative separation of. the plunger and casing as will position the pump piston within the area of the slotted portion 37 of "the pump cylinder, it is of course apparent that no pumping operation, that is no introduction of additional pressure into. the main" pressure chamber, will result, as the pressure is simply transferred around the piston due to the slots.

What I claim is 1. A fluid pressure device comprising a casing, a plunger therein, said plunger being formed to provide an oil reservoir, and a storage chamber arranged below such reservoir, pumping elements carried by the casing and plunger, an oil duct extending lengt wise the plunger and opening thru the side wall of the plunger at one end and into the storage chamber at the opposite end, said duct serving to transfer excess oil from between the plunger and casin to the storage chamber, and packing carrie by the plunger to cooperate with the casing above and below the upper opening of the oil duct.

meme? 2. A fluid pressure device comprising a casing, a plunger movable therein, said plunger being hollow and formed with a centrally upwardly extending neck, a pum cylinder secured to the plunger and exten thru and spaced from the Wall of said neck, a pump piston operating in the cylinder and secured to the casing, a plate closing the upper end of the plunger and formed with an opening to register with the space between the pump cylinder and neck, and plunger cushioning means secured at one end by said plate.

3. A fluid pressure device comprising a casing, a plunger movable therein, said plunger being hollow and formed with a centrally upwardly extending neck, a pum cylinder secured to the plunger and exten ing thru and spaced from the wall of said neck, a pump piston operating in the cylinder and secured to the casing, a plate closing the upper end of the plunger and formed with an opening to re ister with the space between the pump cy 'nder and neck, a springarranged between the casing and plunger, a spring retainer, and means engaging the upper end of the pump cyl- V inder to fix said retainer and plate in position.

4. A fluid pressure device comprising a tive in the relative movement of the casingand plunger for pumping aption, said pump cylinder being of uniform diameter thruout and formed for a limited area to permit the piston pressure to balance on opposite sides of the piston when the piston is operating within such area.

5. A fluid pressure device comprising a casing, a plunger movable therein, a pump including a pump cylinder and piston operative in therelative movement of the casing and plunger for pumping action, said pump cylinder being formed thruout a determinate portion thereof with slots, and means for closing the slots beyond the cylinder.

6. A fluid pressure device comprising a casing, a plunger movable therein, a pump including a pump cylinder and piston operative in the relative movement of the casing and plunger for pumping action, said pump cylinder being formed thruout a determinate portion thereof with slots, and a plate secured to the exterior of the cylinder to overlie and close said slots.

7. A fluid pressure device, comprising a casing, a plunger movable therein, a pump including a pump cylinder and piston opera tive in the relative movement of the casing and plunger for pumping action, said pump cylinder being formed throughout a determinate portion thereof with slots, whereby to prevent pressure action of the piston when working within the area of said slots.

In testimony whereof I afiix my signature,

FRANKLIN EMBRY POINDEXTER. 

